package model;
// 通过该类的对象 完成针对数据库blog表的操作 Data Access

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class BlogDao {
    // 1. 新增操作(提交博客)
    public void insert(Blog blog){
        Connection connection = null;
        PreparedStatement statement = null;
        try {
            // 1. 建立连接
            connection = DBUtil.getConnection();
            // 2. 构造SQL
            String sql = "insert into blog values(null, ?, ?, now(), ?)";
            statement = connection.prepareStatement(sql);
            statement.setString(1, blog.getTitle());
            statement.setString(2, blog.getContent());
            statement.setInt(3, blog.getUserId());
            statement.executeUpdate();
        } catch (SQLException e){
            throw new RuntimeException();
        } finally {
            DBUtil.close(connection, statement,null);
        }
    }

    // 2. 查询博客列表
    public List<Blog> getBlogs(){
        List<Blog> blogList = new ArrayList<>();
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            connection = DBUtil.getConnection();
            String sql = "select * from blog order by postTime desc";
            statement = connection.prepareStatement(sql);
            resultSet = statement.executeQuery();
            while (resultSet.next()){
                Blog blog = new Blog();
                blog.setBlogId(resultSet.getInt("blogId"));
                blog.setTitle(resultSet.getString("title"));
                // 此处读到的是博客的全部，在博客列表里 只希望读到一小部分，做一个简单的截断
                String content = resultSet.getString("content");
                if(content.length() > 100){
                    content = content.substring(0, 100) + "...";
                }
                blog.setContent(content);
                blog.setPostTime(resultSet.getTimestamp("postTime"));
                blog.setUserId(resultSet.getInt("userId"));
                blogList.add(blog);
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            DBUtil.close(connection, statement, resultSet);
        }
        return blogList;
    }

    // 3. 根据博客 ID 查找指定的博客
    public Blog getBlog(int blogId){
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            // 1. 建立连接
            connection = DBUtil.getConnection();
            // 2. 构造 SQL
            String sql = "select * from blog where blogId = ?";
            statement = connection.prepareStatement(sql);
            statement.setInt(1,blogId);
            resultSet = statement.executeQuery();
            // 查询结果非0即1
            if (resultSet.next()) {
                Blog blog = new Blog();
                blog.setBlogId(resultSet.getInt("blogId"));
                blog.setTitle(resultSet.getString("title"));
                blog.setContent(resultSet.getString("content"));
                blog.setPostTime(resultSet.getTimestamp("postTime"));
                blog.setUserId(resultSet.getInt("userId"));
                return blog;
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            DBUtil.close(connection, statement, resultSet);
        }
        return null;
    }

    // 4. 根据博客 ID删除博客
    public void delete(int blogId){
        Connection connection = null;
        PreparedStatement statement = null;
        try {
            connection = DBUtil.getConnection();
            String sql = "delete from blog where blogId = ?";
            statement = connection.prepareStatement(sql);
            statement.setInt(1,blogId);
            statement.executeUpdate();
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            DBUtil.close(connection, statement, null);
        }
    }
}
